[T3] Now a brake glitch

[Jim Adney]

On 28 Oct 2015 at 13:25, Tim Keohane wrote:

> I have my old calipers, and will ship them off to you for inspection
> and assessment when you get home. ( They are ATE with VW cast in both
> and 33 on one and 40 on the other)I believe I replaced them in early
> 2000-2001. My goal is to get these brakes to last for more miles than
> the ones I'm taking out. These were shimmed and then ground a touch to
> get clearance from the wheel which is stock. 

The ones you just took off required shimming? If so, they are not the 
right ones for your car. Or it's possible that you have the wrong 
rotors, which might require that the caliper be shimmed to get the 
rotor centered in the caliper.  

I can tell more once I see your old calipers. ATe made brake parts 
for many makes, using the same or similar castings to machine into 
slightly different applications. If they don't fit right, shimming 
and grinding may get them to fit, but they probably also have 
different piston diameters, etc, which is a problem.

Your brakes are a system. All the parts were chosen to work together 
to give you the best braking for your car. Changing one part out of 
that system is likely to move you away from the optimum that VW 
chose. There are a LOT of choices that VW had to go thru to find a 
good system. The 3 piston diameters (caliper, rear cyl, MC) work 
together with the rotor and drum diameters to give you good brake 
balance, so all 4 wheels are equally useful when braking. The MC 
stroke has to be enough to activate all 4 wheels, even when the rear 
brakes are somewhat worn and out of adjustment or when one half of a 
tandem system fails.

> Is there a way to check the rebuilt ones for quality of parts and
> rebuild?

You can look to see if all the parts shown in the Bentley exploded 
view are there. You can check to see if the cutouts in the piston are 
rotated correctly, per the Bentley. You can make sure the piston 
positioning plates are correctly installed, so that they are on the 
bottom when installed. That's about all you can see without pulling 
the pistons out.

> I'm not heavily experienced at brakes but have lots of mechanical
> time on my commercial fishing vessels in Alaska. 

I'm sure you're up to the mechanics; it's just that you probably 
don't know what to look for in these calipers. And, more importantly, 
the real problem is that most rebuilders won't do this all correctly. 
Maybe they don't know; maybe they don't care; maybe they just want to 
save money, but I hate to buy rebuilds, largely because I almost 
always end up redoing some part of the job myself. (And I NEVER buy 
Type 3 rebuilds, simply because I know how to do them correctly 
myself.)

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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